java练习题

package org.spc.system.api.controller.v1;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.util.ArrayList;
import java.util.List;

public class TxtTest {

//1. 读取文件内容
public static String txt2String(File file){
    StringBuilder result = new StringBuilder();
    try{
        BufferedReader br = new BufferedReader(new FileReader(file));//构造一个BufferedReader类来读取文件
        String s = null;
        while((s = br.readLine())!=null){//使用readLine方法，一次读一行

            result.append(System.lineSeparator()+s);
        }
        br.close();
    }catch(Exception e){
        e.printStackTrace();
    }
    return result.toString();
}
//2. 循环语句分行
public static List<String> txt2Line(File file){
    List<String> lineList = new ArrayList<>();
    try{
        BufferedReader br = new BufferedReader(new FileReader(file));//构造一个BufferedReader类来读取文件
        String s = null;
        while((s = br.readLine())!=null){//使用readLine方法，一次读一行
            lineList.add(s);
        }
        br.close();
    }catch(Exception e){
        e.printStackTrace();
    }
    return lineList;
}

//3. 每一行用循环语句分出单个数据
public static List<String> txt2Line(String str){
    List<String> list = new ArrayList<>();
    String[] as = str.split(",");
    for (int i = 0; i < as.length; i++) {
        System.out.println(as[i]);
    }
    return list;
}
//4.每个数据利用华氏转换成摄氏并输出
public static int f2c(String str){
    int C;
    int F = Integer.parseInt(str);
    C = (F - 32)*5/9;
    System.out.println(C);
    return C;
}
//5. 将最后的字符写入文件中
public static void WriteStringToFile(String filePath,List<String> c) {
    try {
        StringBuffer str = null;
        FileOutputStream fos = new FileOutputStream(filePath);
        for(String s:c){
            str.append(s+",");
        }
        fos.write(str.toString().getBytes());
        fos.close();
    } catch (Exception e) {
        e.printStackTrace();
    }
}


public static void main(String[] args){
    //获取文件
    File file = new File("TxtTest.txt");
   //1. 读取文件内容
    System.out.println(txt2String(file));
    //2. 循环语句分行
    List<String> lineList= txt2Line(file);
    //3. 每一行用循环语句分出单个数据
    List<String> strList=new ArrayList();
    for(String str:lineList){
        strList.addAll(txt2Line(str));
    }
    List<String> c=new ArrayList();
    //4.每个数据利用华氏转换成摄氏并输出
    for(String s:strList){
        c.add(f2c(s)+"");
    }
    //5. 将最后的字符写入文件中
    String filePath="newTxtTest.txt";
    WriteStringToFile(filePath,c);


}

}